Diopter
Diopter
Diopter (pronounced: /ˈdaɪ.ə.pər/) is a unit of measurement used in optics to determine the optical power of a lens or curved mirror. It is equal to the reciprocal of the focal length measured in meters.
Etymology
The term "diopter" comes from the Greek word dioptrēs, meaning "through view". It was first used in this context by the French mathematician and physicist, Ferdinand Monoyer, in the late 19th century.
Definition
A diopter is defined as the reciprocal of the focal length in meters. For example, a 1 diopter lens brings parallel rays of light to focus at 1 meter. A 2 diopter lens brings them to focus at 1/2 meter, and so on. The power of a lens can be calculated using the formula:
- D = 1/f
where D is the power in diopters and f is the focal length in meters.
Related Terms
- Optics: The scientific study of sight and the behavior of light, or the properties of transmission and deflection of other forms of radiation.
- Focal Length: The distance between the center of a lens or curved mirror and its focus.
- Lens (optics): A piece of glass or other transparent substance with curved sides for concentrating or disseminating light rays.
- Ferdinand Monoyer: A French ophthalmologist, known for introducing the diopter in 1872.
See Also
External links
- Medical encyclopedia article on Diopter
- Wikipedia's article - Diopter
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